Herbicidal N(5-chlorotert.butyl-1,3,4-thiadiazol-2-yl) carboxamides

ABSTRACT

New N-(chlorotert.butylthiadiazolyl) amides are employed to combat undesired vegetation both pre-emergently and postemergently. Cyclopropanecarboxamides are preferred.

United States Patent [191 Doyle, Jr. et al.

[451 Apr. 29, 1975 HERBICIDAL N( 5-CHLOROTERT.BUTYL-l,3,4- THIADlAZOL-Z-YL) CARBOXAMIDES [75] Inventors: William C. Doyle, Jr., Leawood;

Joel L. Kirkpatrick, Overland Park,

both of Kans.

[73] Assignee: Gulf Research & Development Company, Pittsburgh, Pa.

[22] Filed: Aug. 9, 1973 [2]] App]. N0.: 387,096

Related US. Application Data [62] Division of Ser. No. 186.419. Oct. 4, 197i Pat. No

[52] US. Cl 260/3063 D Primary Examiner-R. Gallagher [57] ABSTRACT New N-(chlorotert.butylthiadiazolyl) amides are employed to combat undesired vegetation both preemergently and post-emergently. Cyclopropanecarboxamides are preferred.

2 Claims, No Drawings HERBICIDAL N(5-CHLOROTERT.BUTYL-l,3,4-THIADIAZOL- 2-YL) CARBOXAMIDES This application is a division of US. Ser. No. 186,419 filed Oct. 4, 1971, now US. Pat. No. 3,823,005.

DESCRIPTION OF THE INVENTION We have discovered a new class of herbicidal compounds which with some variation of the selectivity and activity are useful as herbicides to combat unwanted vegetation both preand post-emergently, particularly in the presence of crops such as peanuts and maize. According to the present invention, one mmay combat unwanted vegetation by applying to the locus of the vegetation a herbicidally effective amount of a compound having the structural formula:

in which X represents hydrogen or a chloro substituent, R is hydrogen or a methyl or ethyl substituent and R is selected from methyl, chloromethyl, ethyl, propyl, isopropyl, cyclopropyl, chloropropyl, and methoxymethyl substituents, preferably cyclopropyl. The novel compounds may be prepared from available starting materials according to procedures of the type specifically exemplified below.

Preparation of 2-Amino-5-( B-chloro-a,a-climethylethyl 1,3,4-thiadiazole To a well stirred suspension of 150 g of thiosemicarbazide and 225 g of B-chloropivolic acid in 500 ml of dioxane heated at reflux temperature was added 262 g of phosphorus oxychloride over a l hr period. When the addition was complete, heating was continued until HCl evolution ceased. After cooling, the supernatant liquid was decanted from the solid mass and 500 ml of water was added. With cooling, sodium hydroxide pellets were added until a pH of was maintained. The resulting precipitate was collected, washed with water and air dried to give 266 g, m.p. l74176 (85%). Re-

crystallization from methanol gave the analytical sam- Anal. Calcd. for C,,,H,,CIN,OS: C, 45.88; H, 6.16; N, 16.05 p e' o o Found: C, 4614; H, 6.20; N, l6.23

TABLE I H3 1 S -c11 TN-C-R 2 l l ll 1 i N R 0 MP Calcd. Found x R R "C C H N C H N H H Cyclopropyl 137-138 46.24 5.43 16.18 46.03 5.43 16.03 H H cH(CH,1, 132-133 45.88 6.16 16.05 46.14 6.20 16.23 H H (II-1,CH,Cl-1, 134-136 45.88 6.16 16.05 45.06 6.04 16.21 H H 214-215 41.11 5.17 17.98 40.90 5.11 17.76 H H (CH,),,C1 116-118 40.55 5.10 14.18 40.38 5.06 13.97 H H -CH- 90-91 40.99 5.33 15.93 41.02 5.36 15.72

CCH, H CH CH(CH,,), 112-113 47.90 6.511 15.23 47.119 6.59 15.16 H CH, C CH,,) 104-105 49.73 6.95 14.50 49.51 6.99 14.37 H CH, CH,C1 84-85 38.3] 4.64 14.89 38.31 4.70 14.93 H CH,CH, Cyclopropyl 82-83 $0.08 6.30 14.60 50.13 6.39 14.70 Cl H Cyclopropyl 156-157 40.83 4.45 14.28 40.86 4.39 14.07 Cl H CH(CH,,1, 176-177 40.55 5.10 14.18 40.80 5.06 14.111

Anal. Calcd. for C,,H,,,CIN,S: C, 37.60; H, 5.26; N, 21.92 Found: C, 37.67; H, 5.47; N, 2220 Preparation of 2-Methylarnino-S-a,a-bis-chlor0methylethyl l ,3,4- thiadiazole To a stirred suspension of 34 g of 4-methylthiosemicarbazide in 150 ml of dioxane was added 60 g of bis-(2,2-chloromethyl)propionyl chloride, then heated to reflux temperature. Carefully, 50 g of phosphorus l 5 oxychloride was added and heating continued until HCl (36%). An analytical sample, m.p. l08-109, was prepared from CH -Cl -petroleum ether Anal. Calcd. for C H CI MS: C, 35.01; H, 4.62; N, 17.50 Found: C, 35.31; H, 4.80; N, 17.66

Preparation of 2-ls0butyrylamido-5-( B-chloro-a,a-dimethylethyl l ,3 ,4-thiadiazole To 6.0 g of 2-amino-5-(B-chloro-a,a-dimethylethyl)- 1,3,4-thiadiazole in 25 ml of pyridine, was added 6.0 g of isobutyryl chloride at room temperature. The reaction was allowed to stir for 3 hours, then was poured into ice water. The resulting solid was collected, washed with water and air dried to give 6.5 g m.p. 129-l31 (81%). An analytical sample was prepared from CH Cl -petroleum ether, m.p. 132-133.

TABLE Continued M.P. Calcd. Found X R R C C H N C H N Cl H CH,CH l45-l46 38.31 4.64 [4.89 38.39 4.8] [4.57 Cl CH, Cyclopropyl lO4-l05 42.86 4.90 I163 43.04 5.02 I180 Cl CH; CH; lZO-lZl 383i 4.64 14 89 38.29 4.75 l4.93 Cl CH, CH,CH, 100-101 4055 5.10 14.18 40.56 5.22 14.23 Cl CH,CH, Cyclopropyl 101-102 44.73 5.32 13.04 44.86 5.22 13.18 Ci (II-CH, CH2CH3 l39- 140 42.59 5.52 13.54 42.68 5.50 l3.55

COM BATlNG UNWANTED VEGETATION The novel herbicides are effective when used both postand pre-emergently. There is described below an illustrative procedure for herbicidal use of the compounds under controlled conditions in the greenhouse so as to obtain data on phytotoxic activity and selectivity.

l. Post-Emergent Use An aqueous dispersion of each active compound was prepared by combining 0.4 gram of the compound wth about 4 ml of a solvent-emulsifier mixture (3 parts of a commercial polyoxyethylated vegetable oil emulsitier, l part xylene, l part kerosene) and then adding water, with stirring, to a final volume of 40 ml.

The species of plants on which each compound was to be tested were planted in 4-inch pots in a greenhouse. Ten to 18 days after emergence of the plants, three pots of each species were sprayed with an aqueous dispersion of the active compound prepared as described above, at a rate of 5 lb of active compound per acre and at a spray volume of 60 gallons per acre. Approximately 1 week after the spray application the plants were observed and the results rated according to 0 the following schedule.

DEGREE OF EFFECT 0 no effect slight effect 2 moderate effect 3 severe effect 4 maximum effect (all plants died) The same rating schedule was employed to judge preemergent results obtained according to the procedure below.

2. Pre-Emergent Use A solution of each active compound was prepared by dissolving 290 mg of the compound to be tested in 200 ml of acetone. Disposable expanded polystyrene trays about 2 l2 inches deep and about 1 square foot in area were prepared and sprayed with the acetone solution at the rate of 10 lb of active chemical per acre of sprayed area and were then covered with about one-fourth inch of soil. Twenty-one days after seeding and treatment the plants were examined and herbicidal effect was rated according to the above schedule.

Both post-emergent and pre-emergent results are set forth in the following table.

9393i 5 9? a asai f 225.?? ra e H 5 I xcn TNWi-R 2 l 1 N- N 0 n H O m b g 0 I: o n w :1 i 8 *3 in x w P- o H- m n 0 o H n H H U rr m o 0 "1 or w 5 \Q H a tsarsssssrrs-=- E 5 BL- my. 3*... ,=1 5- =L .,=2' .5..

ll H Cyclopropy] Post 4 4 4 4 4 4 Pre 4 4 4 4 4 4 4 4 3 4 4 l C il Post 4 4 4 4 4 4 Pro 3 4 4 4 4 4 ,Cil ll Q" Post 4 4 4 4 4 4 Pro .3 4 4 4 4 4 H CH CH CH Post 3 4 2 4 4 4 Pte 2 4 1 3 4 4 H H Cli Post; 1 4 1 4 4 4 Pro 2 4 1 2 3 3 l! H Cll Cll -Cll Post 2 4 1 3 3 3 Pro 2 4 l 3 4 4 it n -Cll D- CH p 4 4 2 4 4 CH n -(H3 -C H Post 4 4 3 4 4 4 CH p 4 4 4 4 4 4 -13 'C(C}|3)3 POSt 1. 2 1 4 4 3 Free 2 4 4 2 4 4 i1 -Ch CH -C] Post; 1 1 O 4 4 1 Pro 4 4 4 4 4 TABLE [1- Continued to n 4 5 5r 8 3 n iw it n x m v *4 o n. w z; 10 b H 0 H P U rf W O G "J I! w L1 \D H 3 a r2sr.::&r::" 2. Bl-.. M. 12 BL. 55. It; vw J2.--) .H-P'..-v. ii. E 8 H -c,r Cyclopropy] Post 3 4 3 4 4 4 Pro 2 4 2 4 3 4 C1 ll Cyulopvopyl Post 4 4 4 4 4 Pre 4 4 4 4 4 4 1| Cl 1| 4% 3 c Post 4 4 2 4 4 4 3 Pro 2 4 3 4 4 4 I C l 4 Post 4 4 4 4 4 4 Pro 4 4 4 4 4 4 w-w -w Post 4 4 4 4 4 4 (*1 m -Cll Post. 1 4 3 4 4 4 c1 cu c n Post 4 4 4 4 4 4 Pro 4 4 4 4 4 4 Cl C li Cyciopropy] p t 4 4 3 4 4 4 c1 c r c 11 p 1 4 2 4 4 4 Other compounds of closely related structure were .TABLE III also tested by the procedure described above, with results which indicate that small differences in structure use of Herbicides on Twent Species may have critical efl'ects on phytotoxicity. For example, no useful herbicidal activity was observed in comcompound Nm 1 pounds havmg the structural formula:

CH S CH CH 5 CH l 3 \2 I 3 3 CH -c (5H2 l i H 3 41 i: i: H ti Cl N N R 0 Plant Pre Post Species 3lb/A l lb/A 3 lb/A l lb/A The preferred herbicide for use in combating un- 45 C06 ebur 3 2 4 4 wanted vegetation accordmg to the method of this in- Wuam, 4 4 4 4 vention is the compound having the structural formula: m 2 2 1 2 WlId Buckwheat 4 3 4 4 Wild Mustard 4 4 4 4 5O Barnyard Gras 4 3 4 t CH Crabsrw 4 4 4 3 H S 2 Downy Brome l O 4 3 i 3 Giant Foxtail 4 4 4 3 CH "C N-C-CH CH Green Foxtail 4 3 4 3 3 H i it i 2 Nutsedge 0 0 1 0 2 L1 i i ii Shattercane 3 2 3 0 l N H 0 wild Oats 4 0 4 4 Alfalfa 2 0 4 4 Cotton 4 l 4 4 Peanut O 0 2 2 4 4 4 4 In a further test carried out in a manner similar to the 235m 4 4 4 4 procedure described above, this compound was com- Tomato 1 0 4 4 6O Corn 2 O l 0 pared with two other similar compounds on 24 species Grain sorghum 3 2 3 0 of plants. Results were scored according to the same Rice 4 2) 2 3 Wheat t rating schedule as above and appear below in Table III.

Use of Herbicides on Twenty-four S'oecies Plant Species III Compound No 2 Pre Cocklebur Lambsquartcr Morning Glory Pigwee Wild Buckwheat Wild Mustard Barnyard Grass Crabgrass Downy Brome Giant Foxmil bAu-hbbb-hluubbbbubhhbbb Use of Herbicides on Twenty-four Species Plant Species TABLE I II Compound No 3 cm s cl-cn -c CH 1 ll I ll H O Posl We claim:

I. N-(5-Chlorotert'.butyl-l ,3,4-thiadiazol-2-yl) cyclopropanecarboxamide.

2. N-( 5-a,a-Bischloromethylethyl-l ,3 ,4-thiadiazol- 2-yl) propionamide. 

1. N-(5-A,A-CHLOROTERT, BUTYL-1,3,4-THIADIAZOL-2-YL) CYCLOPROPANECARBOXAMIDE.
 2. N-(5-A,A-BISCHLOROMETHYLETHYL-1,3,4-THIADIAZOL-2-YL) PROPIONAMIDE. 